AlCoCrFeNi_(1.9)(Mo, Nb, Hf, C) high entropy alloy strengthened by a novel long-period stacking ordered (LPSO) structure and (Nb, M)C (M = Mo, Hf, Cr)

摘要

AlCoCrFeNi2.1 alloy was widely studied as a typical balanced strength-ductility high-entropy alloy (HEA) and was declared a promising superalloy. Here, for the first time, a small amount of Mo, Nb, Hf, C elements were added to produce multiple carbides to improve further the properties of the alloy. And the nano-scale phase formed during annealing was used to strengthen the alloy. Compared with AlCoCrFeNi2.1 alloy, the tensile strength of the new AlCoCrFeNi1.9(Mo, Nb, Hf, C) HEA at 973 K increased from 538 to 771 MPa without decreasing in ductility. During annealing, a novel nano-scale long-period stacking ordered (LPSO) phase with (Ni, Al)-rich formed. And it increased the yield and tensile strengthes of the alloy at room temperature from 498 to 1008 MPa and from 858 to 1242 MPa without decreasing in ductility. The tensile properties of the alloy at 973 K were not significantly improved by the LPSO phase.